1. Field of the Invention
Exemplary embodiments of the present invention relate to a visible ray sensor and a light sensor including the same. More particularly, exemplary embodiments of the present invention relate to a visible ray sensor and a light sensor capable of improving photosensitivity by preventing photodegradation.
2. Discussion of the Background
Liquid crystal displays (LCDs) are one of the most widely-used flat panel displays. An LCD may include a pair of panels provided with field-generating electrodes and a liquid crystal (LC) layer interposed between the two panels. The LCD may display images by applying signals to the field-generating electrodes to generate an electric field in the LC layer that determines the orientation of LC molecules therein to adjust polarization of incident light.
Recently, research on LCDs additionally having a touch sensing function or an image sensing function has been undertaken. To realize the touch sensing function and the image sensing function, a light sensor including an infrared ray sensor and a visible ray sensor may be added to the liquid crystal display.
Light sensors in a LCD may be exposed for a long time while sensing incident light. The semiconductor layer used as the light sensor may be exposed such that a dangling bond is formed. This results in the recombination of holes and electrons and the emission of heat. Accordingly, charge carriers may decrease and the electrical conductivity may deteriorate resulting in decreased photosensitivity. This problem is further described with reference to the accompanying drawings.
FIG. 1 is a graph showing a photocurrent behavior according to exposure time for a conventional visible ray sensor. FIG. 2 is a view comparing a region of an LCD exposed to light and a region that is not exposed to light in the conventional visible ray sensor.
As can be appreciated from FIG. 1, photocurrent gradually decreases as the exposure time increases. Thus, if the visible ray sensor is exposed for a long time, the electrical conductivity may deteriorate such that the photosensitivity also deteriorates.
Accordingly, the amount of the photocurrent generated in a region where the light is irradiated and a region where the light is not irradiated may differ, thereby resulting in the appearance of stains in the LCD.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.